The invention concerns a method and arrangements for controlling the print current in metal paper printers. It is known for information recording in metal paper printers to be effected by applying a voltage, in the course of which an arc is formed, between a print electrode and a record carrier provided with a thin metallized layer. This arc causes the metal layer of the record carrier to be burnt out at the position of the electrode.
Conventional driver circuits for supplying the print voltage and the print current, respectively, were provided with a switching transistor comprising a current limiting resistor. By means of this original solution relatively thin metal layers could be satisfactorily burnt out but with thicker metal layers defects (areas which were not burnt out) were encountered. The cause of such defects was that the maximum current (as a result of the current limiting resistor at a predetermined voltage) was insufficient. A corresponding increase of the print voltage and thus of the print current, however, would have led to thinner metal layers being unduly and excessively burnt out. Thus, for metal papers with a greater tolerance range for the thickness of the vapor deposited metal layer the print quality would have been insufficient: either as a result of defects in the thicker areas of the metal layer or as a result of excessively burnt out areas in the thinner regions of the metal layer.